Immobilized functional group

Kelly and Leyden10 studied the interaction of APTS with silica gel by thermometric enthalpy titration. This technique provides information regarding kinetic and thermodynamic parameters, which govern the reactivity of immobilized functional groups. They found that 26% of the APTS molecules were irreversibly bonded to the silica surface and attributed this stability to ionic interactions. Both values are equal within experimental error. 

The anchor is defined as a resin-immobilized functional group which forms a cleavable coupling to the first building block used in the synthesis. This means that a linker becomes an anchor after it is immobilized on a resin. The different names are important,... 

The methods for oligomerization of the peptoid monomers are broadly based on the techniques developed for solid-phase peptide synthesis. A number of modifications are necessary, since difficulties are often encountered with N-alkyl amino acids for example, proHne and other N-alkylamino acids often couple poorly under standard conditions. Currently a wide range of functionalized polystyrenes and polystyrene copolymers is available. The immobilized functional group typically is an amino, carboxy, halo, hydroxy, or phosphino group. The polymer is joined to the... 

Other immobilization methods are based on chemical and physical binding to soHd supports, eg, polysaccharides, polymers, glass, and other chemically and physically stable materials, which are usually modified with functional groups such as amine, carboxy, epoxy, phenyl, or alkane to enable covalent coupling to amino acid side chains on the enzyme surface. These supports may be macroporous, with pore diameters in the range 30—300 nm, to facihtate accommodation of enzyme within a support particle. Ionic and nonionic adsorption to macroporous supports is a gentle, simple, and often efficient method. Use of powdered enzyme, or enzyme precipitated on inert supports, may be adequate for use in nonaqueous media. Entrapment in polysaccharide/polymer gels is used for both cells and isolated enzymes. 

Compounds 167-171 outlined in Fig. 43 form another series of diboronic acids that form complexes with mono- and disaccharides. In these cases the asymmetrical immobilization of chromophoric functional groups, e.g., aromatic rings in 167-170 or Fe -complexation with the related boronate 171, can be analyzed by circular dichroism measurements [256-262]. 

When the rhodium-catalyzed reaction is performed under a high pressure of CO in the presence of phosphite ligands, aldehyde products (159) are formed by insertion of CO into the rhodium-alkyl bond followed by reductive elimination (Eq. 31) [90]. The bimetallic catalysts were immobilized as nanoparticles, giving the same products and functional group tolerance, with the advantage that the catalyst could be recovered and reused without loss of... 

---